I am seeing to get a tarpon120 sit on top kayak and would like to know if I would be able to take this in the ocean... Normally very close to the shoreline and not to far out, would this be possible? And if I were taking in a calm yet mild river would it be suitable?

The short answer to both questions is "Yes". The long answer warns against off shore winds, strong tidal streamsand the likelihood of being more exposed to wind/wetness/coldl than in a conventional boat (relevant if you are padddling at this time of year).

From your question it appears that you aren't thinking of surfing it, but since you have posted in the surf kayaking section of the forum [moderator's note - now moved] I thought it was worth mentioning that most sit on tops don't surf at all well due to the long keel. There are some sit-on tops that will surf, but they tend not to be so good for journeys.

Of course you can - in the same way as you can climb Ben Nevis in trainers if the weather is fine.
Make your own judgement call on the weather forecast and local conditions ballanced with your own skills / capabilities / experience and, if you think it's safe, then why not. It will be hard work, compared to a sit-in kayak, as SOTs tend to be a bit broader in the beam and heavier so have much more wetted surface area to slow them down compared to a sit-in boat of the same length.

The short answer to both questions is "Yes". The long answer warns against off shore winds, strong tidal streamsand the likelihood of being more exposed to wind/wetness/coldl than in a conventional boat (relevant if you are padddling at this time of year).

I had a 120 as my first boat and agree with all the above, of course you can take it on the ocean. Few points to think about, first one is that in the beginning, mine is around 10 years old now, they had a problem with leaking front hatches, in ‘conditions’ with water coming over the front of the boat they will ship a bit of water, and having only a single internal compartment with no bulkheads this can cause a problem, so when I paddled mine frequently I always carried a pump. Second point, which might also perhaps have been cured over time, is that the rear bung was tucked away out of sight and low down on the stern, really silly position for it, as if you drain the boat out at the end of a trip by standing it on its stern and removing the bung, it’s then possible to set out on your next trip with the the bung out, I did this, and it led to one of only two times so far that I’ve unintentionally ended up in the water from a sit on top. The huge plus, of course, is that it’s really easy to get back on board if you fall off.

The vast majority of kayak fishermen tend to use SoTs due to their added stability and that they are often paddling shorter distances.
If you have any specific questions about SoTs in general or that model and its suitability you may want to try post in the Kayak Angling pages.

Make sure you have some flotation inside the hull if possible; if the hull leaks then you could be in trouble.

You may also want to connect a tow rope to the kayak as a leash and carry an easily accessible safety knife. For me the biggest risk is that if you become separated from the kayak it sits quite high in the water and can be blown away from you very quickly.